Impeccable rhymes with:
amicable, applicable, bankable, breakable, communicable, despicable, drinkable, eradicable, explicable, extricable, implacable, impracticable, inapplicable, ineradicable, inextricable, irrevocable, likable, likeable, practicable, remarkable, revocable, talkable, unbreakable, unmistakable, unremarkable, unshakable, unshakeable, unsinkable, unspeakable, unthinkable, unworkable, workable
Impeccable sounds like:
impassable, impassively, impeachable, impeccably, impossible, impossibly, infeasible, invisible